Antenna for wireless distribution systems



P. C. HEWITT. ANTENNA FOR WIRELESS DISTRIBUTJON SYSTEMS;

APPLICATION FILED AUG. 12, 1916. 7 1,305,104. Patented May 27, 1919.

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P. C. HEWITT. ANTENNA FOR WIRELESS DISTRIBUTION SYSTEMS.

APPLICATION FILED AUG I2. I916- Patented May 27, 1919.

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ANTENNA FOR WIRELESS DISTRIBUTION SYSTEMS.

APPLICATION FILED AUG. 12, 1916. 1,305,104.

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PETER COOPER HEWITT, 0F RINGWOOD MANOR, NEW JERSEY.

ANTENNA FOR WIRELESS DISTRIBUTION SYSTEMS.

Specification of Letters Patent.

Patented May 27, 1919.

Applicationfiled August 12, 1916. Serial No. 114,527.

T 0 all whom it may concern:

Be it known that I, PETER COOPER HEWITT, a citizen of the'United States,and resident of Ringwood Manor, county of Passaic, State of New Jersey,have invented certain new and useful Improvements in Antennae.

for IVireless Distribution Systems, of which the following is aspecification.

This invention has for its object increasing the radiating power of anaerial by means of increasing the voltage to which the aerial may beraised without loss due to corona effect. The invention consists inconstructing the diameter of the aerial along its length and its variousparts in direct rela tion to the voltage which the aerial at any pointis required to sustain. It is known that the dielectric strength of airto resist corona effect for small isolated conductors is about 7 0,000to 80,000 volts and, in order to increase the dielectric strength of airsurrounding a conductor, it is necessary to increase .the diameter ofthe conductor. On increasing the diameter of a conductor subjected tothe strain of a definite voltage, the dielectric value of the airimproves until a certain diameter is attained, after which increase indiameter has .but little practical value. Such ratio is expressedapproximately by the formula Volts:3%0,000 dianieter in inches+40,000.

This formula is derived from data com iled from actual tests by theWestinghouse lectric & Manufacturing Company of Pittsburgh,Pennsylvania, in connection with high tension transmission work.

My invention is embodied in an aerial having an increasing diameter fromthe conductors used at the ground end, to a diameter of 6 inches, orthereabout, at the terminal end. The end should be insulated by means ofan insulator in practically the same manner and of substantially thesame construction as high voltage transmission lines are now insulated.With such an arrangement the terminal voltage to which the aerial maybeoperated without coronaeffect or leakage loss may be, or may evenexceed, 600,000 volts, while with the ordinary wire and insulator, thecorona loss incident thereto may be attained below 100,000 volts,therebyrendering operation impractical at such high voltage. The energythat may be radiated from an aerial increases in some direct ratio asthe operating voltage of the aerial is increased. Therefore, an aerialas herein described, will be capable of greater radiation than one ofordinary wire, since the voltage to which it may 'be raised withoutcorona is many times greater. When current leaks away into air from aconductor raised to a high voltage, it produces a luminous effect aroundthe surface of the conductor: this is herein called corona effect, andthe loss incident thereto is called corona loss.

My aerial may be constructed of flat wire, woven basket fashion, so asto be 6 inches in diameter at the end, or it may be made birdcagefashion of wires held close together, or be made of sheet metal,orotherwise fashioned. For convenience, the aerial may at parts of itslength, be larger in diameter than as herein described as necessary, butshould not be smaller, except that it has electrostatic effect imposedon it as would be the case in internal convolutions of a spiral.

My invention is illustrated inthe accompanying drawings in which Figures1, 2, 3, 4, 5, 6, 7 and 8 show various forms of construction of myantenna; Figs. 9, 10 and 11 show curves plotted from data compiled bythe WVestinghouse Electric & Manufacturing Company in connection withhigh tension transmission work, and

Fig. 12 shows a curve deduced from the curve of Figs. 9, 10 and 11.

Referring to Fig. 1, 1 is a T shaped aerial, the ground end 2 beingconnected to the exciting circuits of any suitable type.

In Fig. 2, 3 is a vertical straight antennatapered from its base, 4, toits tip, 5, in such a manner that the diameter at any point isproportional to the voltage between said point and the ground end 4.

In Fig. 3 is shown an enlarged view of the antenna of Fig. 1 looking atthe tip 6. It will be noted that the antenna 1 is hollow and as shown inFig. 1 gradually increases in diameter from the point 2 to the ends 6and 7.

In Fig. at I have shown a construction suitable for my antenna whereinflat pieces 8, 8, are woven basket fashion.

Fig. 5 is an elevation of the joint 9 in Fig. 1 and Fig. 6 is a sectionof Fig. 5 showing the taper from the point 9 to the end 6 and. thehollow construction of the vertical part 1.

Fig. 7 is a section through YY, of Fig. 1, and Fig. 8 shows an enlargedelevation of the antenna of Fig. 1 below the line YY.

In Fig. 9 I show a set of curves which illustrate the effect of thediameter of two parallel wires on the voltage at which corona will format four different distances between the wires. The curves of Fig. 10 aresimilar to thoseof Fig. 9 but are plotted on a difierent scale and showthe effect of the diameter of the conductors for small separation. Thecurve of Fig. 11 illustrates the effect of the diameter of a spherecharged to one hundred thousand volts on the separation between it and aplate necessary to prevent the formation of corona. The curve of Fig. 12shows approximately the relation between the diameter of a conductorseparated a considerable distance from the ground and the potential atwhich .the conductor can be maintained above that of the ground withoutcorona .loss. For instance, if it is desired to maintain a certain pointin an antenna at 5%"611 hundred and twenty thousand volts (720,000) itwill be necessary to make the diameterv of the antenna conductor at thatpoint two inches.

I claim as my invention:

1. A tapering antenna having a diameter at its tip greater than adiameter at the ground and of such a size at all pointsthat a coronawill not form under the conditions of operation.

- 2. A non-leaking, high voltage, antenna having its diameter at anypoint propor-' tional to the voltage between said point and the ground.

3. A non-leaking, high voltage, antenna so constructed that its diameterat any point and the voltage at any point shall be as represented inFig. 12. I

4. A non-leaking, high voltage, antenna for a wireless transmissionsystem consisting of a conductor greater than 3.5 inches in diameter atits tip and tapered so that the diameter at any point is nowhere lessthan proportional to the voltage between said point and the ground.

5. A non-leaking, high voltage, tapering conductor grounded at one endand greater than 3.5 inches in diameter at the other end.

6. A non-leaking, high voltage, antenna for wireless electric circuitsconsisting of a conductor presenting an external surface graduallyincreasing toward one end, the ratio of the increment correspondingapproximately to that of the normal movement of tendency toward coronalosses.

7. In a wireless telephone or telegraph system, a non-leaking, highvoltage, antemia having 'a diameter at each point such that throughoutits effective length the tendency to form corona is equalized.

Signed at New York, in the county of New York and State of New York,this 27th day of July, A. D. 1916.

PETER COOPER HEWITT.

Witnesses: WALTER E. F. BRAQLEY,

JOHN F. NELSON.

